<?php

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/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 5.1.6 or newer
 *
 * @package		CodeIgniter
 * @author		ExpressionEngine Dev Team
 * @copyright	Copyright (c) 2008 - 2011, EllisLab, Inc.
 * @license		http://codeigniter.com/user_guide/license.html
 * @link		http://codeigniter.com
 * @since		Version 1.0
 * @filesource
 */

// ------------------------------------------------------------------------


/**
 * SQLSRV Database Adapter Class
 *
 * Note: _DB is an extender class that the app controller
 * creates dynamically based on whether the active record
 * class is being used or not.
 *
 * @package		CodeIgniter
 * @subpackage	Drivers
 * @category	Database
 * @author		ExpressionEngine Dev Team
 * @link		http://codeigniter.com/user_guide/database/
 */
class CI_DB_sqlsrv_driver extends CI_DB {
	
	var $dbdriver = 'sqlsrv';
	
	// The character used for escaping
	var $_escape_char = '';
	
	// clause and character used for LIKE escape sequences
	var $_like_escape_str = " ESCAPE '%s' ";
	var $_like_escape_chr = '!';
	
	/**
	 * The syntax to count rows is slightly different across different
	 * database engines, so this string appears in each driver and is
	 * used for the count_all() and count_all_results() functions.
	 */
	var $_count_string = "SELECT COUNT(*) AS ";
	var $_random_keyword = ' ASC'; // not currently supported
	

	/**
	 * Non-persistent database connection
	 *
	 * @access	private called by the base class
	 * @return	resource
	 */
	function db_connect($pooling = false) {
		// Check for a UTF-8 charset being passed as CI's default 'utf8'.
		$character_set = (0 === strcasecmp ( 'utf8', $this->char_set )) ? 'UTF-8' : $this->char_set;
		
		$connection = array ('UID' => empty ( $this->username ) ? '' : $this->username, 'PWD' => empty ( $this->password ) ? '' : $this->password, 'Database' => $this->database, 'ConnectionPooling' => $pooling ? 1 : 0, 'CharacterSet' => $character_set, 'ReturnDatesAsStrings' => 1 );
		
		// If the username and password are both empty, assume this is a
		// 'Windows Authentication Mode' connection.
		if (empty ( $connection ['UID'] ) && empty ( $connection ['PWD'] )) {
			unset ( $connection ['UID'], $connection ['PWD'] );
		}
		
		return sqlsrv_connect ( $this->hostname, $connection );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Persistent database connection
	 *
	 * @access	private called by the base class
	 * @return	resource
	 */
	function db_pconnect() {
		$this->db_connect ( TRUE );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Reconnect
	 *
	 * Keep / reestablish the db connection if no queries have been
	 * sent for a length of time exceeding the server's idle timeout
	 *
	 * @access	public
	 * @return	void
	 */
	function reconnect() {
		// not implemented in MSSQL
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Select the database
	 *
	 * @access	private called by the base class
	 * @return	resource
	 */
	function db_select() {
		return $this->_execute ( 'USE ' . $this->database );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Set client character set
	 *
	 * @access	public
	 * @param	string
	 * @param	string
	 * @return	resource
	 */
	function db_set_charset($charset, $collation) {
		// @todo - add support if needed
		return TRUE;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Execute the query
	 *
	 * @access	private called by the base class
	 * @param	string	an SQL query
	 * @return	resource
	 */
	function _execute($sql) {
		$sql = $this->_prep_query ( $sql );
		return sqlsrv_query ( $this->conn_id, $sql, null, array ('Scrollable' => SQLSRV_CURSOR_STATIC, 'SendStreamParamsAtExec' => true ) );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Prep the query
	 *
	 * If needed, each database adapter can prep the query string
	 *
	 * @access	private called by execute()
	 * @param	string	an SQL query
	 * @return	string
	 */
	function _prep_query($sql) {
		return $sql;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Begin Transaction
	 *
	 * @access	public
	 * @return	bool
	 */
	function trans_begin($test_mode = FALSE) {
		if (! $this->trans_enabled) {
			return TRUE;
		}
		
		// When transactions are nested we only begin/commit/rollback the outermost ones
		if ($this->_trans_depth > 0) {
			return TRUE;
		}
		
		// Reset the transaction failure flag.
		// If the $test_mode flag is set to TRUE transactions will be rolled back
		// even if the queries produce a successful result.
		$this->_trans_failure = ($test_mode === TRUE) ? TRUE : FALSE;
		
		return sqlsrv_begin_transaction ( $this->conn_id );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Commit Transaction
	 *
	 * @access	public
	 * @return	bool
	 */
	function trans_commit() {
		if (! $this->trans_enabled) {
			return TRUE;
		}
		
		// When transactions are nested we only begin/commit/rollback the outermost ones
		if ($this->_trans_depth > 0) {
			return TRUE;
		}
		
		return sqlsrv_commit ( $this->conn_id );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Rollback Transaction
	 *
	 * @access	public
	 * @return	bool
	 */
	function trans_rollback() {
		if (! $this->trans_enabled) {
			return TRUE;
		}
		
		// When transactions are nested we only begin/commit/rollback the outermost ones
		if ($this->_trans_depth > 0) {
			return TRUE;
		}
		
		return sqlsrv_rollback ( $this->conn_id );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Escape String
	 *
	 * @access	public
	 * @param	string
	 * @param	bool	whether or not the string will be used in a LIKE condition
	 * @return	string
	 */
	function escape_str($str, $like = FALSE) {
		// Escape single quotes
		return str_replace ( "'", "''", $str );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Affected Rows
	 *
	 * @access	public
	 * @return	integer
	 */
	function affected_rows() {
		return @sqlrv_rows_affected ( $this->conn_id );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Insert ID
	 *
	 * Returns the last id created in the Identity column.
	 *
	 * @access public
	 * @return integer
	 */
	function insert_id() {
		return $this->query ( 'select @@IDENTITY as insert_id' )->row ( 'insert_id' );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Parse major version
	 *
	 * Grabs the major version number from the
	 * database server version string passed in.
	 *
	 * @access private
	 * @param string $version
	 * @return int16 major version number
	 */
	function _parse_major_version($version) {
		preg_match ( '/([0-9]+)\.([0-9]+)\.([0-9]+)/', $version, $ver_info );
		return $ver_info [1]; // return the major version b/c that's all we're interested in.
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Version number query string
	 *
	 * @access public
	 * @return string
	 */
	function _version() {
		$info = sqlsrv_server_info ( $this->conn_id );
		return sprintf ( "select '%s' as ver", $info ['SQLServerVersion'] );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * "Count All" query
	 *
	 * Generates a platform-specific query string that counts all records in
	 * the specified database
	 *
	 * @access	public
	 * @param	string
	 * @return	string
	 */
	function count_all($table = '') {
		if ($table == '')
			return '0';
		
		$query = $this->query ( "SELECT COUNT(*) AS numrows FROM " . $this->dbprefix . $table );
		
		if ($query->num_rows () == 0)
			return '0';
		
		$row = $query->row ();
		return $row->numrows;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * List table query
	 *
	 * Generates a platform-specific query string so that the table names can be fetched
	 *
	 * @access	private
	 * @param	boolean
	 * @return	string
	 */
	function _list_tables($prefix_limit = FALSE) {
		return "SELECT name FROM sysobjects WHERE type = 'U' ORDER BY name";
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * List column query
	 *
	 * Generates a platform-specific query string so that the column names can be fetched
	 *
	 * @access	private
	 * @param	string	the table name
	 * @return	string
	 */
	function _list_columns($table = '') {
		return "SELECT * FROM INFORMATION_SCHEMA.Columns WHERE TABLE_NAME = '" . $this->_escape_table ( $table ) . "'";
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Field data query
	 *
	 * Generates a platform-specific query so that the column data can be retrieved
	 *
	 * @access	public
	 * @param	string	the table name
	 * @return	object
	 */
	function _field_data($table) {
		return "SELECT TOP 1 * FROM " . $this->_escape_table ( $table );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * The error message string
	 *
	 * @access	private
	 * @return	string
	 */
	function _error_message() {
		$error = array_shift ( sqlsrv_errors () );
		return ! empty ( $error ['message'] ) ? $error ['message'] : null;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * The error message number
	 *
	 * @access	private
	 * @return	integer
	 */
	function _error_number() {
		$error = array_shift ( sqlsrv_errors () );
		return isset ( $error ['SQLSTATE'] ) ? $error ['SQLSTATE'] : null;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Escape Table Name
	 *
	 * This function adds backticks if the table name has a period
	 * in it. Some DBs will get cranky unless periods are escaped
	 *
	 * @access	private
	 * @param	string	the table name
	 * @return	string
	 */
	function _escape_table($table) {
		return $table;
	}
	
	/**
	 * Escape the SQL Identifiers
	 *
	 * This function escapes column and table names
	 *
	 * @access	private
	 * @param	string
	 * @return	string
	 */
	function _escape_identifiers($item) {
		return $item;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * From Tables
	 *
	 * This function implicitly groups FROM tables so there is no confusion
	 * about operator precedence in harmony with SQL standards
	 *
	 * @access	public
	 * @param	type
	 * @return	type
	 */
	function _from_tables($tables) {
		if (! is_array ( $tables )) {
			$tables = array ($tables );
		}
		
		return implode ( ', ', $tables );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Insert statement
	 *
	 * Generates a platform-specific insert string from the supplied data
	 *
	 * @access	public
	 * @param	string	the table name
	 * @param	array	the insert keys
	 * @param	array	the insert values
	 * @return	string
	 */
	function _insert($table, $keys, $values) {
		return "INSERT INTO " . $this->_escape_table ( $table ) . " (" . implode ( ', ', $keys ) . ") VALUES (" . implode ( ', ', $values ) . ")";
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Update statement
	 *
	 * Generates a platform-specific update string from the supplied data
	 *
	 * @access	public
	 * @param	string	the table name
	 * @param	array	the update data
	 * @param	array	the where clause
	 * @param	array	the orderby clause
	 * @param	array	the limit clause
	 * @return	string
	 */
	function _update($table, $values, $where) {
		foreach ( $values as $key => $val ) {
			$valstr [] = $key . " = " . $val;
		}
		
		return "UPDATE " . $this->_escape_table ( $table ) . " SET " . implode ( ', ', $valstr ) . " WHERE " . implode ( " ", $where );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Truncate statement
	 *
	 * Generates a platform-specific truncate string from the supplied data
	 * If the database does not support the truncate() command
	 * This function maps to "DELETE FROM table"
	 *
	 * @access	public
	 * @param	string	the table name
	 * @return	string
	 */
	function _truncate($table) {
		return "TRUNCATE " . $table;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Delete statement
	 *
	 * Generates a platform-specific delete string from the supplied data
	 *
	 * @access	public
	 * @param	string	the table name
	 * @param	array	the where clause
	 * @param	string	the limit clause
	 * @return	string
	 */
	function _delete($table, $where) {
		return "DELETE FROM " . $this->_escape_table ( $table ) . " WHERE " . implode ( " ", $where );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Limit string
	 *
	 * Generates a platform-specific LIMIT clause
	 *
	 * @access	public
	 * @param	string	the sql query string
	 * @param	integer	the number of rows to limit the query to
	 * @param	integer	the offset value
	 * @return	string
	 */
	function _limit($sql, $limit, $offset) {
		$i = $limit + $offset;
		
		return preg_replace ( '/(^\SELECT (DISTINCT)?)/i', '\\1 TOP ' . $i . ' ', $sql );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Close DB Connection
	 *
	 * @access	public
	 * @param	resource
	 * @return	void
	 */
	function _close($conn_id) {
		@sqlsrv_close ( $conn_id );
	}

}



/* End of file mssql_driver.php */
/* Location: ./system/database/drivers/mssql/mssql_driver.php */